The objective of this proposal is to determine the macromolecular structures and interactions responsible for maintaining the gel structure of the adult vitreous. The studies will be concerned with the structure and properties of the major extracellular constituents, collagen, glycoproteins and hyaluronic acid. In vivo studies will be carried out to determine the extent to which these constituents are resynthesized and vitreous structure is regenerated following vitrectomy in rabbits. The in vitro experiments concerned with the structures and interactions between the vitreous macromolecular constituents will be performed with preparations obtained from the bovine. Whenever possible the results of these experiments will be correlated with studies carried out on vitreous samples obtained from humans at autopsy. The principal methods to be used will be amino acid analysis, disc-gel electrophoresis, column chromatographic procedures, optical rotation, circular dichroism, vitrectomy in rabbits and incorporation of radioactive intermediates by the eye tissues, analytical ultracentrifugation and electron microscopy.